JP7087551B2 - Control device - Google Patents

Description

The present invention relates to a control device applied to a vehicle equipped with an internal combustion engine and a storage battery.

Conventionally, in some vehicles, idling stop control is performed in order to improve fuel efficiency (for example, Patent Document 1). In Patent Document 1, a target SOC of a battery (storage battery) as a charging target is set in consideration of the amount of power consumed by auxiliary equipment (air conditioner or the like) during idling stop control. This prevents the SOC of the battery from becoming less than the predetermined lower limit threshold of the usable SOC range even if the power of the battery is consumed by the accessories during the idling stop control.

Therefore, it is possible to prevent the SOC of the battery from reaching the lower limit and restarting the engine during the idling stop control, that is, before the restart condition is satisfied. Therefore, the period during which the idling stop control is performed becomes long, and the fuel efficiency can be improved. The restart condition is satisfied, for example, on the condition that the brake is released or the accelerator is operated.

Japanese Patent No. 5842927

However, the power that can be output by the battery changes not only with the SOC but also with the deterioration state of the battery, the temperature, and the like. Therefore, even if the SOC of the battery is within the usable SOC range, it is necessary to supply the power required to restart the engine or to stably operate the electric load connected to the battery. It may not be possible to continue the idling stop state, such as when power cannot be supplied. For example, in a low temperature state, even if the SOC of the battery is within the usable SOC range, it may not be possible to supply the voltage required for restarting the engine.

In such a case, in order to avoid the situation where the engine cannot be restarted due to insufficient battery output, the power that can be output by the battery is taken into consideration even if the SOC of the battery is within the usable SOC range. , It is necessary to restart the engine. Therefore, since the control device described in Patent Document 1 does not consider the power that can be output by the battery, it is often the case that the engine is restarted during idling stop control and before the restart condition is satisfied. It can occur. That is, there is a possibility that the fuel efficiency cannot be sufficiently improved.

The present invention has been made in view of the above circumstances, and a main object thereof is to provide a control device capable of improving fuel efficiency.

In order to solve the above problems, the first means are an internal combustion engine, an internal combustion engine, a starter for starting the internal combustion engine, a storage battery that can be charged and discharged, and an electric load to which electric power is supplied from the storage battery. The stop control unit that stops the internal combustion engine to shift to the idling stop state when the automatic stop condition is satisfied, and the restart condition is satisfied in the idling stop state. It is the remaining capacity of the start control unit that controls the starter so as to restart the internal combustion engine, and the storage battery that is determined to be able to continue the idling stop state based on the state of the storage battery. Based on the lower limit value estimation unit that estimates the lower limit value, the power consumption estimation unit that estimates the power consumption consumed by the electric load during the idling stop state, and the lower limit value estimated by the lower limit value estimation unit. In consideration of the power consumption estimated by the power consumption estimation unit, the setting unit is provided with a setting unit for setting a permitted value which is the remaining capacity of the storage battery that permits the transition to the idling stop state.

The permission value for permitting the transition to the idling stop state is set with reference to the lower limit value and in consideration of the power consumption in the idling stop state. Therefore, if the remaining capacity of the storage battery is equal to or greater than the permitted value and the idling stop state is entered, it is possible to prevent the storage battery from falling below the lower limit value during the idling stop state.

The lower limit is the remaining capacity of the storage battery that is judged to be able to continue the idling stop state, and the value is set based on the state of the storage battery (state related to output performance such as temperature and deterioration state). Will be done. That is, since the lower limit value is estimated according to the state of the storage battery, even if the state of the storage battery changes, if the remaining capacity of the storage battery is larger than the lower limit value, the power for continuing the idling stop state should be secured. Can be done.

From the above, it is possible to prevent the internal combustion engine from being restarted below the lower limit value or becoming impossible to restart before the restart condition is satisfied during the idling stop state. .. As a result, the period of idling stop state can be lengthened, and fuel efficiency can be further improved.

The lower limit is set in order to stably operate the electric load by the remaining capacity of the storage battery, which is the minimum required for restarting the internal combustion engine, or by supplying electric power from the storage battery in the idling stop state. It is estimated based on the minimum required remaining capacity of the storage battery.

Therefore, if the remaining capacity of the storage battery is larger than the lower limit, the remaining capacity of the storage battery, which is the minimum required for restarting the internal combustion engine, or the power supply from the storage battery in the idling stop state stabilizes the electric load. It is possible to secure the minimum remaining capacity of the storage battery required for operation.

Further, the vehicle is provided with a generator capable of generating electricity by the driving energy of the internal combustion engine or the kinetic energy of the vehicle, and the storage battery is configured to be rechargeable by the power supplied from the generator. A power generation control unit for controlling the power generation of the generator is provided so that the remaining capacity of the generator becomes equal to or higher than the target value, and the target value is set higher than the permitted value.

Therefore, before shifting to the idling stop state, it is possible to secure the amount of power consumption consumed by the electric load during the idling stop state.

Schematic block diagram showing an in-vehicle power supply system. A flowchart showing the idling stop process. A flowchart showing power generation processing. A time chart showing SOC transitions. A time chart showing SOC transitions. The schematic block diagram which shows the in-vehicle power supply system in another example. The schematic block diagram which shows the in-vehicle power supply system in another example.

Hereinafter, embodiments will be described with reference to the drawings. In the present embodiment, an electronic control device (engine ECU) as a control device is embodied, and the engine ECU supplies power to various devices of the vehicle, for example, in a vehicle traveling with an engine (internal combustion engine) as a drive source. It is used as a control device applied to the in-vehicle power supply system to be supplied. In each of the following embodiments, the parts that are the same or equal to each other are designated by the same reference numerals, and the description thereof will be used for the parts having the same reference numerals.

As shown in FIG. 1, the in-vehicle power supply system is a dual power supply system including a lead storage battery 11 and a lithium ion storage battery 12, and power can be supplied from the storage batteries 11 and 12 to the electric loads 13 and 15. ing. Further, each of the storage batteries 11 and 12 can be charged and discharged by the rotary electric machine 14. In this system, the lead storage battery 11 and the lithium ion storage battery 12 are connected in parallel to the rotary electric machine 14, and the lead storage battery 11 and the lithium ion storage battery 12 are connected in parallel to the electric load 15.

The lead storage battery 11 is a well-known general-purpose storage battery. On the other hand, the lithium ion storage battery 12 is a high-density storage battery having a smaller power loss in charging / discharging, a higher output density, and a higher energy density than the lead storage battery 11. The lithium ion storage battery 12 is preferably a storage battery having higher energy efficiency during charging / discharging than the lead storage battery 11. Further, the lithium ion storage battery 12 is configured as an assembled battery each having a plurality of cell cells. The rated voltage of each of these storage batteries 11 and 12 is the same, for example, 12V.

Although a specific description by illustration is omitted, the lithium ion storage battery 12 is housed in a storage case and is configured as a battery unit U integrated with a substrate. In FIG. 1, the battery unit U is shown surrounded by a broken line. The battery unit U has external terminals P0, P1 and P2, of which the lead-acid battery 11 and the electric load 13 are connected to the external terminal P0, the rotary electric machine 14 is connected to the external terminal P1, and the external terminal P2 is connected. The electrical load 15 is connected.

The rotary electric machine 14 is a generator with a motor function having a three-phase AC motor and an inverter as a power conversion device, and is configured as an ISG (Integrated Starter Generator) integrated with mechanical and electrical power. The rotary electric machine 14 is mechanically connected to the engine 10. The rotary electric machine 14 has a power generation function of generating power (fuel power generation) by driving energy of an engine output shaft and power generation (regenerative power generation) by rotating energy of an axle (kinetic energy of a vehicle). The rotary electric machine 14 supplies the generated power to the storage batteries 11 and 12 and the electric load 15. Further, the rotary electric machine 14 has a power running function of applying a rotational force to the engine output shaft. The rotary electric machine 14 is supplied with electric power for carrying out the power running function from the lithium ion storage battery 12.

For example, the rotary electric machine 14 can start the engine 10 by applying a rotational force to the engine output shaft when the operating state of the engine 10 is in the stopped state. Therefore, the rotary electric machine 14 has a function as a starter. Further, the rotary electric machine 14 has a so-called torque assist function of applying a rotational force (torque assist) to the axle or the engine output shaft to assist the traveling of the vehicle.

The electric load 15 includes a constant voltage load in which the voltage of the supplied power is required to be constant or fluctuate within a predetermined range. The electric load 15 can be said to be a protected load. Further, it can be said that the electric load 15 is a load to which a power failure is not allowed.

Specific examples of the electric load 15 which is a constant voltage required load include a navigation device, an audio device, a meter device, various ECUs including an engine ECU 50, and the like. In this case, by suppressing the voltage fluctuation of the supplied power, unnecessary resets and the like are suppressed in each of the above-mentioned devices, and stable operation can be realized. The electric load 15 may include a traveling system actuator such as an electric steering device or a braking device.

The electric load 13 is a general electric load other than the constant voltage required load. Specific examples of the electric load 13 include a seat heater, a heater for a defroster of a rear window, a headlight, a wiper of a front window, a blower fan of an air conditioner, and the like.

Next, the battery unit U will be described. The battery unit U is provided with an electric path L1 connecting the external terminals P0 and P1 and an electric path L2 connecting the connection point N1 on the electric path L1 and the lithium ion storage battery 12 as an electric path in the unit. .. Of these, the switch SW1 is provided in the electric path L1, and the switch SW2 is provided in the electric path L2. The generated power of the rotary electric machine 14 is supplied to the lead storage battery 11 and the lithium ion storage battery 12 via the electric paths L1 and L2.

Speaking of the electric path from the lead storage battery 11 to the lithium ion storage battery 12, the switch SW1 is provided on the side of the lead storage battery 11 (the side of the external terminal P0) with respect to the connection point N1 and the lithium ion storage battery is provided with respect to the connection point N1. A switch SW2 is provided on the side of the twelve.

Further, in the battery unit U of the present embodiment, in addition to the electric paths L1 and L2, electricity connecting the connection point N2 (the point between the external terminal P0 and the switch SW1) on the electric path L1 and the external terminal P2. It has a path L4. The electric path L4 forms a path that enables power to be supplied from the lead storage battery 11 to the electric load 15. A switch SW4 is provided in the electric path L4 (specifically, between the connection point N2- and the connection point N4).

Further, in the battery unit U, the connection point N3 of the electric path L2 (the point between the switch SW2 and the lithium ion storage battery 12) and the connection point N4 on the electric path L4 (the point between the switch SW4 and the external terminal P2) , Is provided with an electric path L3 for connecting the above. The electric path L3 forms a path that enables power to be supplied from the lithium ion storage battery 12 to the electric load 15. A switch SW3 is provided in the electric path L3 (specifically, between the connection point N3 and the connection point N4). In terms of the electric path from the lead storage battery 11 to the lithium ion storage battery 12, the switch SW4 is provided on the side of the lead storage battery 11 with respect to the connection point N4, and the switch SW3 is provided on the side of the lithium ion storage battery 12 with respect to the connection point N4. It is provided.

The battery unit U includes a BMU 18 (battery management device, battery management unit) that controls each switch SW1 to SW4. The BMU 18 is composed of a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like. The BMU 18 controls the states (on, off) of the switches SW1 to SW4.

Further, the BMU 18 acquires the state of the lithium ion storage battery 12 and outputs a signal (information) indicating the state of the lithium ion storage battery 12. The state of the lithium ion storage battery 12 is, for example, the temperature, deterioration state, output voltage, and SOC of the lithium ion storage battery 12.

That is, the BMU 18 calculates (acquires) the SOC (residual capacity: State Of Charge) of the lithium ion storage battery 12, and outputs a signal (information) indicating the SOC. The SOC may be calculated by a well-known method. For example, the SOC is calculated based on the open circuit voltage (OCV) in the power cutoff state, and the current energized during charging / discharging of the lithium ion storage battery 12 is integrated at a predetermined cycle. Then, the SOC may be updated sequentially. In the following, the SOC of the lithium ion storage battery 12 may be simply referred to as SOC.

Further, the BMU 18 monitors (acquires) the deterioration state of the lithium ion storage battery 12, and outputs a signal (information) indicating the deterioration state. The deterioration state monitoring method may be a well-known method. For example, the internal resistance of the lithium ion storage battery 12 is calculated by using a set of the voltage between terminals of the lithium ion storage battery 12 and the charge / discharge current, and the internal resistance is calculated. It may be used to monitor the deterioration state of the lithium ion storage battery 12.

Further, the BMU 18 acquires the temperature of the lithium ion storage battery 12 from a temperature sensor (not shown) that detects the temperature of the lithium ion storage battery 12, and outputs a signal (information) indicating the temperature. Further, the BMU 18 acquires the output voltage of the lithium ion storage battery 12 from a voltage sensor (not shown) that detects the output voltage of the lithium ion storage battery 12, and outputs a signal (information) indicating the output voltage.

The engine ECU 50 (hereinafter, simply referred to as ECU 50) is an electronic control device including a well-known microcomputer including a CPU, ROM, RAM, flash memory, and the like. The ECU 50 is configured to be able to acquire various information. For example, the ECU 50 acquires (inputs) driver operation information from various sensors such as an accelerator sensor that detects an accelerator operation amount and a brake sensor that detects a brake operation amount of a brake pedal. Further, the ECU 50 acquires information indicating the state of the lithium ion storage battery 12 from the BMU 31. Further, the ECU 50 acquires information (vehicle speed, etc.) about the vehicle from various sensors such as a vehicle speed sensor. Further, the ECU 50 acquires information regarding the driving state of the electric load 15 from the electric load 15.

Then, the ECU 50 executes various controls based on the acquired various information. For example, the ECU 50 controls the power running drive and power generation of the rotary electric machine 14 based on the vehicle speed, driver operation information, and the like. At that time, the ECU 50 controls the charging and discharging of the lithium ion storage battery 12 based on the SOC of the lithium ion storage battery 12 and the like.

Specifically, the ECU 50 instructs the BMU 18 of the battery unit U so that the SOC of the lithium ion storage battery 12 is maintained within a predetermined range of use. The predetermined range of use is a flat range (so-called plateau region) where the voltage change is small on the charge / discharge curve. The BMU 18 controls the switches SW1 to SW4 based on the instruction from the ECU 50 to control the charging and discharging of the lithium ion storage battery 12.

Further, the ECU 50 controls the operating state (including start and stop) of the engine 10. For example, the ECU 50 implements idling stop control of the engine 10 as control of the operating state of the engine 10. In the idling stop control, as a general rule, the operation (combustion) of the engine 10 is stopped when a predetermined automatic stop condition is satisfied, and then the engine 10 is restarted when a predetermined restart condition is satisfied. In this case, the automatic stop condition includes, for example, that the vehicle speed is in the engine automatic stop speed range (for example, vehicle speed ≦ 10 km / h), the accelerator operation is released, or the brake operation is performed. Further, the restart condition includes, for example, that the accelerator operation is started and that the brake operation is released. Further, the ECU 50 also has a function of determining that the explosion has been completed (that is, the restart has been completed) after the engine 10 has been restarted. It is also possible to configure the engine control function and the idling stop function to be performed by separate ECUs.

By the way, since it is necessary to continuously supply electric power to the electric load 15 which is a constant voltage required load, the SOC of the lithium ion storage battery 12 will continue to decrease even in the idling stop state. Therefore, in the conventional control device, the power consumption consumed by the electric load during the idling stop state is predicted, and the power consumption is taken into consideration, and the minimum secured standard before shifting to the idling stop state. The threshold value as SOC was set.

Specifically, in the conventional control device, the threshold value is set by adding the storage capacity corresponding to the predicted power consumption to the lower limit of the usage range of the lithium ion storage battery. Then, the conventional control device charges and discharges the storage battery so that the SOC of the lithium ion storage battery does not fall below the threshold value. Therefore, during the idling stop state, the SOC of the storage battery becomes the lower limit of the usage range due to the power consumption due to the electric load, and the situation where the engine is restarted before the restart condition is satisfied is suppressed.

However, the output power of the lithium ion storage battery 12 changes depending on the state of the lithium ion storage battery 12 (state related to the output performance) such as the deterioration state and temperature of the lithium ion storage battery 12. For example, when the lithium ion storage battery 12 is deteriorated, or when the temperature is high or low, the output power of the lithium ion storage battery 12 may be reduced even if the SOC is the same.

Therefore, when the threshold value is set based on the lower limit of the usage range of the lithium ion storage battery 12 at a certain time (for example, in the initial state) as in the conventional case, there are the following problems. That is, when the state of the lithium ion storage battery 12 such as the deteriorated state or the temperature of the lithium ion storage battery 12 changes, the output power may be reduced and the power required to maintain the idling stop state may not be secured.

Therefore, in the present embodiment, the charging / discharging of the lithium ion storage battery 12 and the idling stop control are executed in consideration of the state of the lithium ion storage battery 12. Hereinafter, it will be described in detail.

The ECU 50 has various functions as shown below. That is, as shown in FIG. 1, the ECU 50 includes a lower limit value estimation unit 51, a power consumption estimation unit 52, a setting unit 53, a stop control unit 54, a start control unit 55, and a power generation control unit 56. To prepare for. Various functions of these functions are realized by executing a control program stored in a ROM or the like included in the ECU 50. The various functions may be realized by electronic circuits that are hardware, or at least a part of them may be realized by software, that is, processing executed on a computer.

The lower limit value estimation unit 51 estimates the lower limit SOC (lower limit value) which is the SOC of the lithium ion storage battery 12 which is the minimum required for restarting the engine 10 based on the state of the lithium ion storage battery 12. The lower limit SOC is the SOC of the storage battery that is judged to be able to continue the idling stop state. Specifically, when the engine 10 is restarted, the minimum required SOC and the electric load 15 are stably operated in order to output the electric power required by the rotary electric machine 14 that applies the rotational force to the engine 10. It is determined based on the higher SOC of the minimum required SOCs in order to output the power required for this.

Specifically, map data for specifying the lower limit SOC is created in advance with the deterioration state and temperature of the lithium ion storage battery 12 as parameters, and stored in the storage device of the ECU 50. Then, the lower limit value estimation unit 51 estimates the lower limit SOC based on the deterioration state and the temperature of the lithium ion storage battery 12 acquired from the BMU 18 with reference to the map data.

The power consumption estimation unit 52 estimates the power consumption consumed by the electric load 15 during the idling stop state. The power consumption is the amount of power consumed by the electric load 15 from the start of the idling stop state to the elapse of a predetermined time. In the present embodiment, the predetermined time is a constant value, and it is desirable that the predetermined time is set in consideration of the time (for example, 1 to 2 minutes) in which the idling stop state is likely to be maintained. A predetermined time may be set based on the travel history and peripheral information described later.

The power consumption is estimated with reference to the map data based on the driving state of the electric load 15. The drive state includes not only on / off but also a certain amount of required power. This drive state is output from the electric load 15. Map data when the electric load 15 with a large required power amount is in the ON state, when the required power amount of the electric load 15 in the ON state is large, or when a large number of electric loads 15 are in the ON state, etc. Based on this, it is easy to estimate that the amount of power consumption is high. On the other hand, when the electric load 15 having a large required power amount is in the off state, when the required power amount of the electric load 15 in the on state is small, or when a large amount of electric load 15 is in the off state, etc. Based on the map data, it is easy to estimate that the power consumption is low.

The setting unit 53 sets the permitted SOC (permitted value) based on the lower limit SOC estimated by the lower limit value estimation unit 51 and in consideration of the power consumption estimated by the power consumption estimation unit 52. The permitted SOC is the SOC of the lithium ion storage battery 12 as a reference for permitting the transition to the idling stop state. Specifically, the setting unit 53 sets the permitted SOC by adding the storage capacity required for supplying the estimated power consumption to the lower limit SOC.

The stop control unit 54 stops the engine 10 and shifts to the idling stop state when the automatic stop condition is satisfied, provided that the SOC of the acquired lithium ion storage battery 12 is equal to or higher than the permitted SOC. Whether or not the automatic stop condition is satisfied is determined based on the vehicle speed, driver operation information, and the like as described above.

The start control unit 55 controls the rotary electric machine 14 so as to restart the engine 10 when the restart condition is satisfied in the idling stop state. Whether or not the restart condition is satisfied is determined based on the driver operation information and the like as described above. Even if the restart condition is not satisfied in the idling stop state, the start control unit 55 power-drives the rotary electric machine 14 to drive the engine 10 when the SOC decreases to the lower limit SOC. To restart. As a result, it is possible to prevent a situation in which the output power becomes insufficient and the restart cannot be performed, an unstable operation of the electric load 15, and the like.

The power generation control unit 56 controls the power generation of the rotary electric machine 14 so that the SOC becomes equal to or higher than the target SOC (target value). When the SOC is less than the upper limit of the usage range and the regenerative power generation is possible based on the kinetic energy of the vehicle such as during deceleration, the power generation control unit 56 rotates the rotary electric machine 14 by the kinetic energy of the vehicle. The shaft is rotated to cause the rotary electric machine 14 to perform regenerative power generation.

Further, the power generation control unit 56 operates the engine 10 when the SOC of the lithium ion storage battery 12 is less than the target SOC and the situation is such that regenerative power generation is not possible based on the kinetic energy of the vehicle, such as when the lithium ion storage battery 12 is stopped. Then, the power generation control unit 56 rotates the rotary shaft of the rotary electric machine 14 by the drive energy of the engine output shaft, and causes the rotary electric machine 14 to generate power (fuel power generation).

The target SOC is set at least higher than the permitted SOC. That is, the target SOC is set by providing a predetermined margin in the permitted SOC. Specifically, a value obtained by multiplying the permitted SOC by a predetermined magnification (for example, 1.2 times) is set by the setting unit 53 as the target SOC. Since the permitted SOC is set based on the lower limit value and the power consumption amount, it can be said that the target SOC set based on the permitted SOC is also set based on the lower limit value and the power consumption amount.

The setting unit 53 may set a target SOC by adding a predetermined capacity to the permitted SOC. It is desirable that the predetermined capacity is, for example, a storage capacity capable of continuing the idling stop state for about several minutes. Further, in the present embodiment, the target SOC is set by the setting unit 53, but the target SOC may be set as a constant value in the storage device in advance. At that time, among the SOCs assumed as permitted SOCs, a value larger than the maximum value may be set as a reference.

Further, the ECU 50 permits the rotary electric machine 14 to perform the torque assist function on condition that the SOC of the lithium ion storage battery 12 is larger than the target SOC. The ECU 50 causes the rotary electric machine 14 to execute power running drive on the condition that the SOC is larger than the target SOC when it is determined that the vehicle is accelerating or traveling at a constant speed based on the driver operation information and the vehicle speed. To assist the vehicle running.

Next, the idling stop process related to the idling stop control will be described with reference to FIG. 2. The idling stop process is periodically executed by the ECU 50 after the ignition switch is turned on.

First, the ECU 50 as the lower limit value estimation unit 51 estimates the lower limit SOC based on the deterioration state and temperature of the lithium ion storage battery 12 acquired from the BMU 18 with reference to the map data (step S101). Next, the ECU 50 as the power consumption estimation unit 52 estimates the power consumption consumed by the electric load 15 during the idling stop state based on the driving state of the electric load 15 (step S102).

Then, the ECU 50 as the setting unit 53 sets the permitted SOC with reference to the lower limit SOC estimated in step S101 and in consideration of the power consumption estimated in step S102 (step S103). The ECU 50 determines whether or not the SOC of the lithium ion storage battery 12 is larger than the permitted SOC (step S104). If this determination result is negative, the idling stop process is terminated.

On the other hand, if the determination result in step S104 is affirmative, the ECU 50 acquires vehicle speed and driver operation information, and determines whether or not the automatic stop condition is satisfied based on the acquired information (step S105). If this determination result is negative, the idling stop process is terminated.

On the other hand, if the determination result in step S104 is affirmative, the ECU 50 as the stop control unit 54 stops the engine 10 and shifts to the idling stop state (step S106).

Next, the ECU 50 determines whether or not the restart condition is satisfied (step S107). If this determination result is affirmative, the ECU 50 as the start control unit 55 controls the rotary electric machine 14 so as to restart the engine 10 (step S108). As a result, the idling stop state is terminated and the idling stop process is terminated.

On the other hand, if the determination result in step S107 is negative, the ECU 50 acquires the SOC of the lithium ion storage battery 12 and determines whether or not the acquired SOC is larger than the lower limit SOC (step S109). If this determination result is affirmative, the ECU 50 re-executes step S107 after a predetermined time has elapsed. That is, the idling stop state is continued until the restart condition is satisfied or the SOC reaches the lower limit SOC.

On the other hand, if the determination result in step S109 is negative, the ECU 50 shifts to step S108 and controls the rotary electric machine 14 so as to restart the engine 10. That is, the engine 10 is restarted regardless of the restart condition. Then, the idling stop state is terminated.

Next, with reference to FIG. 3, a power generation process related to power generation by the rotary electric machine 14 will be described. The power generation process is executed at predetermined intervals by the ECU 50 as the power generation control unit 56.

The ECU 50 acquires the SOC of the lithium ion storage battery 12 and determines whether or not the acquired SOC is less than the upper limit of the usage range of the lithium ion storage battery 12 (step S201).

If the determination result in step S201 is negative, the power generation process is terminated. On the other hand, if the determination result in step S201 is affirmative, the ECU 50 determines whether or not the situation is such that regenerative power generation is possible by using the kinetic energy of the vehicle (step S202). In step S202, the ECU 50 determines that the accelerator is not operated, that the brake is operated, or that the vehicle speed is decelerating, based on the driver operation information and the vehicle speed. In this case, it is determined that the kinetic energy of the vehicle can be used to generate regenerative power.

If this determination result is affirmative, the ECU 50 uses the kinetic energy of the vehicle to control the rotary electric machine 14 so as to carry out regenerative power generation (step S203). Then, the ECU 50 ends the power generation process.

On the other hand, if the determination result in step S202 is negative, the ECU 50 determines whether or not the acquired SOC is less than the target SOC (step S204). In step S204, the ECU 50 may set the target SOC based on the permitted SOC, or in step S103, the target SOC may be set together with the permitted SOC. If this determination result is negative, the power generation process is terminated. On the other hand, if the determination result in step S204 is affirmative, it is determined whether or not the idling stop state is in effect (step S205). If this determination result is affirmative, the ECU 50 ends the power generation process.

On the other hand, if the determination result in step S205 is negative, the ECU 50 controls the operation of the engine 10 and controls the rotary electric machine 14 to generate power by using the drive energy of the engine output shaft (step S206). .. That is, fuel power generation is carried out. When the vehicle is accelerating, the engine 10 is operated so as to output an extra load corresponding to the load required for power generation. On the other hand, when the vehicle is stopped (when it is idling), the engine 10 is operated so as to output the load required for power generation.

Next, in FIGS. 4 and 5, the SOC transition when the idling stop state is executed will be described. In FIGS. 4 and 5, the SOC transition in the conventional example is shown by a alternate long and short dash line, and the SOC transition in this example is shown by a solid line. In the conventional example, the lower limit of the usage range of the lithium ion storage battery 12 is used as a reference, and the sum of the storage capacities corresponding to the power consumption of the electric load 15 is set as the minimum threshold to be secured before the idling stop state (conventional example). .. In this embodiment, it is assumed that the lower limit of the usage range of the lithium ion storage battery 12 and the power consumption of the electric load 15 are the same values as those of the conventional example. Further, the state of the lithium ion storage battery 12 is the same between the conventional example and the present embodiment, and the minimum SOC required for restarting the engine 10 (lower limit SOC of the present embodiment) is lower than the lower limit of the usage range. The explanation is based on the assumption that it is high. Further, in FIG. 4, the initial value of the SOC is the same in the present embodiment and the conventional example, and will be described on the premise that the value is higher than the target SOC.

First, the situation of the vehicle speed in FIG. 4 will be described. As shown in FIG. 4, the vehicle travels at a constant speed in the period from time point T1 to T4, decelerates in the period from time point T4 to T5, and stops in the period after time point T5.

Next, on the premise of this vehicle situation, the SOC transition in the conventional example will be described. When the vehicle travels at a constant speed from the time point T1 to the time point T3, as shown by the alternate long and short dash line, the SOC is equal to or higher than the threshold value (conventional example), so that the rotary electric machine is driven by power running and the electric load consumes electric power. .. As a result, the SOC decreases until the threshold value (conventional example) is reached.

When the vehicle decelerates from the time point T4 to the time point T5, the SOC increases and becomes larger than the threshold value (conventional example) because the rotary electric machine performs regenerative power generation. Then, when the vehicle stops at the time point T5, the automatic stop condition is satisfied, so that the engine shifts to the idling stop state.

When the vehicle is stopped at the time point T5 to the time point T6, the electric load 15 consumes electric power during the idling stop state, so that the SOC becomes lower than the threshold value (conventional example). Then, at the time point T6, when the SOC reaches the minimum required SOC for restarting the engine 10, in order to prevent the restart from being impossible, the idling stop state is set even if the restart condition is not satisfied. Quit and restart the engine. As a result, the SOC does not decrease.

During the period from T6 to T7, the engine is idling and the rotary electric machine generates fuel, so that the SOC rises. When the SOC reaches the threshold value (conventional example) at the time point T7, the automatic stop condition is satisfied, and the state shifts to the idling stop state again.

In the period from the time point T7 to the time point T8, since the idling stop state is in effect, the SOC decreases. Then, at the time point T8, when the SOC reaches the minimum required SOC for restarting the engine 10, the engine is restarted. As a result, the SOC does not decrease. During the period from time point T8 to T9, the engine is in an idling state and the rotary electric machine performs fuel power generation, so that the SOC rises and reaches a threshold value (conventional example).

As described above, in the conventional example, due to the influence of the state of the lithium ion storage battery 12, the SOC becomes the minimum required for restarting before the SOC decreases to the lower limit of the usage range. That is, even if the capacity corresponding to the power consumption is secured with the lower limit of the usage range as a reference, the restart is performed before the capacity is used up, and as a result, the period of the idling stop state is shortened. Therefore, depending on the state of the lithium ion storage battery 12, there is a possibility that restarting may be repeated frequently.

Next, the transition of SOC in this embodiment will be described with reference to FIG. When the vehicle travels at a constant speed from the time point T1 to the time point T2, as shown by the solid line, since the SOC is equal to or higher than the target SOC, the rotary electric machine 14 is driven by power running. As a result, the SOC decreases until the target SOC is reached. When the vehicle travels at a constant speed from the time point T2 to the time point T4, the rotary electric machine 14 does not perform power running drive because the SOC reaches the target SOC. At that time, it is necessary to supply electric power to the electric load 15, but the electric power is supplied from the lead storage battery 11. This keeps the SOC at the target SOC. At this time, the rotary electric machine 14 may be made to perform fuel power generation, and the generated power may be supplied to the electric load 15.

When the vehicle decelerates from the time point T4 to the time point T5, the SOC increases because the rotary electric machine 14 performs regenerative power generation, and becomes larger than the target SOC. Then, when the vehicle stops at the time point T5, the automatic stop condition is satisfied, so that the engine shifts to the idling stop state. When the vehicle is stopped at the time point T5 to the time point T9, the SOC decreases because the electric load 15 consumes the electric power during the idling stop state.

As described above, in this embodiment, the permitted SOC is set with a capacity corresponding to the amount of power consumption secured based on the minimum required lower limit SOC for restarting. Therefore, even if the state of the lithium ion storage battery 12 is changed, it is possible to prevent the period of the idling stop state from being shortened. Along with this, it is possible to suppress repeated restarts and fuel power generation. Since restarting the engine 10 generally requires a large amount of energy, the smaller the number of restarts, the better the fuel efficiency than the larger number. Further, in the conventional example, the power running drive can be carried out longer than in the present embodiment. However, it is generally better to maintain the idling stop state for a long period of time than to carry out the power running drive for a long period of time.

Next, it will be described with reference to FIG. In FIG. 5, in both the conventional example and the present embodiment, the initial value of the SOC is a value that is secured at the minimum before the transition to the idling stop state when the charging time is sufficiently secured. That is, it is assumed that the initial value of the SOC in the conventional example is a threshold value (conventional example), and the initial value of the SOC in the present embodiment is the target SOC.

First, the situation of the vehicle speed in FIG. 5 will be described. As shown in FIG. 5, the vehicle stops in the period from time point T11 to T12, accelerates in the period from time point T12 to T13, decelerates in the period from time point T13 to T14, and stops in the period after time point T14. do.

Next, on the premise of this vehicle situation, the SOC transition in the conventional example will be described with reference to FIG. When the vehicle is stopped at the time point T11, the SOC is a threshold value (conventional example), so that the vehicle shifts to the idling stop state. Then, when the vehicle is stopped from the time point T11 to the time point T12, the SOC decreases because the electric load consumes the electric power during the idling stop state.

When the vehicle accelerates or decelerates from the time point T12 to the time point T14, the SOC is less than the threshold value (conventional example), so that the rotary electric machine generates power (fuel power generation and regenerative power generation), and the SOC increases. At the time point T14, when the vehicle stops, even if the restart condition is satisfied, the SOC is less than the threshold value (conventional example), so that the transition to the idling stop state is not permitted.

Next, the SOC transition in this embodiment will be described. If the vehicle is stopped at the time point T11, the SOC is equal to or higher than the permitted SOC, and the system shifts to the idling stop state. Then, when the vehicle is stopped from the time point T11 to the time point T12, the electric load 15 consumes the electric power during the idling stop state, so that the SOC decreases.

When the vehicle accelerates or decelerates from the time point T12 to the time point T14, the SOC is equal to or higher than the permitted SOC but less than the target SOC. Therefore, the rotary electric machine 14 generates power (fuel power generation and regenerative power generation), and the SOC increases. To go. At this point in time, when the vehicle stops at T14, the SOC is less than the target SOC, but is equal to or higher than the permitted SOC, so that the state shifts to the idling stop state when the restart condition is satisfied.

As shown in FIG. 5, if the restart condition is satisfied in a short period of time after the idling stop state ends, the period for generating power may be short and sufficient charging may not be possible. In this case, in the conventional example, charging could not be performed so that the SOC becomes equal to or higher than the threshold value (conventional example), and the idling stop state could not be entered. On the other hand, in this embodiment, a target SOC larger than the permitted SOC is set as a charging target. Therefore, even if sufficient charging cannot be performed, the SOC can be set to be equal to or higher than the permitted SOC because there is a surplus capacity between the target SOC and the permitted SOC. That is, even if the restart condition is satisfied in a short period of time after the idling stop state ends, it is possible to suppress the opportunity to shift to the idling stop state.

According to the present embodiment described in detail above, the following excellent effects can be obtained.

The permission SOC that permits the transition to the idling stop state is set with reference to the lower limit SOC and in consideration of the power consumption due to the electric load 15 during the idling stop state. Therefore, if the SOC of the lithium ion storage battery 12 is equal to or higher than the permitted SOC and the state shifts to the idling stop state, it is possible to prevent the lithium ion storage battery 12 from becoming less than the lower limit SOC during the idling stop state.

The lower limit SOC is the SOC of the lithium ion storage battery 12 that is the minimum required for restarting, and the value thereof is based on the state of the lithium ion storage battery 12 (state related to output performance such as temperature and deterioration state). , Set. Therefore, even if the state of the lithium ion storage battery 12 changes, if the SOC of the lithium ion storage battery 12 is larger than the lower limit SOC, the electric power required by the rotary electric machine 14 as a starter when restarting the engine 10 can be obtained. Can be secured.

From the above, it is possible to prevent the engine 10 from being restarted below the lower limit SOC or in a situation where restart is impossible before the restart condition is satisfied during the idling stop state. .. As a result, the period of idling stop state can be lengthened, and fuel efficiency can be further improved.

Depending on the road conditions, the automatic stop condition may be satisfied in a short time after restarting. Therefore, if the target SOC as the charging target is matched with the permitted SOC, there is not enough time to recover the SOC by charging depending on the road condition, and there is a high possibility that the opportunity to shift to the idling stop state is missed.

Therefore, we decided to set the target SOC larger than the permitted SOC to allow room for the SOC. As a result, even if there is no time to recover the SOC, since the SOC has a margin in advance in charging, the opportunity to shift to the idling stop state is not missed. Therefore, fuel efficiency can be improved.

The start control unit 55 restarts the engine 10 based on the comparison between the SOC of the lithium ion storage battery 12 and the lower limit SOC before the restart condition is satisfied. That is, when the SOC of the lithium ion storage battery 12 reaches the lower limit SOC, the ECU 50 restarts the engine 10 even before the restart condition is satisfied. As a result, it is possible to reliably avoid a situation in which the SOC falls below the lower limit SOC and the engine 10 cannot be restarted during the idling stop state.

If the rotary electric machine 14 generates fuel while accelerating or traveling at a constant speed, fuel efficiency will deteriorate. However, by prolonging the period of the idling stop state, it is expected that the fuel efficiency will be improved even if the deterioration of the fuel efficiency due to the fuel power generation is taken into consideration. Therefore, when the SOC is less than the target SOC, the rotary electric machine 14 is made to generate fuel even if the vehicle is not decelerating, so that the SOC is equal to or higher than the target SOC. As a result, the period of the idling stop state can be lengthened, and the fuel efficiency can be improved from a comprehensive point of view.

(Other embodiments)
The present invention is not limited to the above embodiment, and may be implemented as follows, for example. In the following, the parts that are the same or equal to each other in each embodiment are designated by the same reference numerals, and the description thereof will be referred to for the portions having the same reference numerals.

-In the above embodiment, the power consumption estimation unit 52 may estimate the power consumption based on the travel history of the vehicle. The travel history is, for example, a history such as the frequency of transition to the idling stop state and the length of one idling stop period. From the travel history, trends such as the transition frequency and the length of one idling stop period can be predicted to some extent. And those tendencies are related to power consumption. Therefore, by adopting the above configuration, it is possible to improve the estimation accuracy of the power consumption.

Specifically, when it is determined from the travel history that the transition frequency is high, the power consumption is increased as compared with the case where it is determined that the transition frequency is low, and when it is determined that the idling stop period is long. , The power consumption may be increased as compared with the case where it is determined to be short. By improving the estimation accuracy of the power consumption, the margin of the SOC can be reduced and the permitted SOC can be lowered. As a result, it becomes easy to shift to the idling stop state, and the fuel efficiency can be improved.

-In the above embodiment, the setting unit 53 may correct the permitted SOC based on the traveling history of the vehicle. For example, when it is determined from the travel history that the frequency of transition to the idling stop state is low, the permitted SOC may be reduced as compared with the case where it is determined that the frequency of transition to the idling stop state is low. Further, when it is determined that the idling stop period is short, the permitted SOC may be reduced as compared with the case where it is determined that the idling stop period is long. By considering the travel history, the SOC margin can be reduced and the permitted SOC can be reduced. As a result, it becomes easy to shift to the idling stop state, and the fuel efficiency can be improved.

-In the above embodiment, the power consumption estimation unit 52 may estimate the power consumption based on the peripheral information of the vehicle. The vehicle peripheral information is, for example, the congestion status of the vehicle (that is, whether or not it is congested), the road width, the number of lanes, the frequency of traffic lights, etc., and includes an in-vehicle camera, an in-vehicle communication device, and the like. Information that can be obtained by using it. When the vehicle is crowded, it is expected that the frequency of transition to the idling stop state will be higher than when the vehicle is not crowded. In addition, when the road width is wide or the number of lanes is large, it is expected that the time for the traffic light to display the stoppage will be longer and the idling stop period will be longer than when the road is narrow or the number of lanes is small. Ru. In addition, when the frequency of passing (discovering) a traffic light per unit time is high, it is expected that the frequency of transition to the idling stop state will be higher than when the frequency is low.

As described above, the frequency of transition to the idling stop state and the length of one idling stop period are related to the amount of power consumption. Therefore, the power consumption estimation unit 52 has decided to acquire the peripheral information of the vehicle and estimate the power consumption based on the acquired peripheral information. Specifically, when it is determined that the vehicle is congested based on the peripheral information, the power consumption may be increased as compared with the case where it is determined that the vehicle is not congested. Further, when it is determined that the road width is wide, the power consumption may be increased as compared with the case where it is determined that the road width is narrow. Further, when it is determined that the number of lanes is large, the power consumption may be increased as compared with the case where it is determined that the number of lanes is small. Further, when it is determined that the frequency of the traffic light is high, the power consumption may be increased as compared with the case where it is determined that the frequency of the traffic light is low.

With the above configuration, the accuracy of estimating the power consumption can be improved. By improving the estimation accuracy of the power consumption, the margin of the remaining capacity can be reduced and the permitted value can be lowered. As a result, it becomes easy to shift to the idling stop state, and the fuel efficiency can be improved.

-In the above embodiment, the setting unit 53 may correct the permission SOC based on the peripheral information of the vehicle. For example, when it is determined that the vehicle is congested based on the peripheral information, the permitted SOC may be set larger than that when it is determined that the vehicle is not congested. Further, when it is determined that the road width is wide based on the information around the vehicle, the permitted SOC may be set larger than that when it is determined that the road width is narrow. Further, when it is determined that the number of lanes is large based on the peripheral information of the vehicle, the permitted SOC may be set larger than that when it is determined that the number of lanes is small. Further, when it is determined that the frequency of the traffic light is high based on the peripheral information of the vehicle, the permitted SOC may be set larger than that when it is determined that the frequency of the traffic light is low.

-In the above embodiment, if the setting unit 53 determines that the time from the start to the stop of the vehicle tends to be short based on the travel history and the surrounding information, the target SOC may be increased. That is, when the setting unit 53 determines that the time from the establishment of the restart condition to the establishment of the automatic stop condition tends to be short based on the travel history and the surrounding information, even if the target SOC is increased. good. As a result, even if the time from the establishment of the restart condition to the establishment of the automatic stop condition is short and the charging time cannot be secured so much, the spare capacity is secured and the opportunity to shift to the idling stop state is provided. It can be suppressed to miss.

-In the above embodiment, when the setting unit 53 determines that the time from the end of the idling stop state to the re-establishment of the automatic stop condition is short based on the travel history of the vehicle or the surrounding information, the permission SOC is determined. And the target SOC may be set. When the time from the end of the idling stop state until the automatic stop condition is satisfied again is short, for example, when the frequency of transition to the idling state is high or when the vehicle is crowded, the frequency of appearance of the traffic light is high. This applies when there are many cases. On the other hand, the setting unit 53 sets only the target SOC when it is determined that it takes a long time from the end of the idling stop state to the establishment of the automatic stop condition again based on the traveling history of the vehicle or the surrounding information. You may. In this case, the target SOC replaces the permitted SOC.

-In the above embodiment, the rotary electric machine 14 is adopted as the starter, but an engine starter may be adopted. In this case, an engine starter may be provided separately from the rotary electric machine 14.

-In the above embodiment, the permitted SOC may be set only after the end of the idling stop state and until the SOC of the lithium ion storage battery 12 becomes equal to or higher than the target SOC. In this case, after the SOC becomes equal to or higher than the target SOC, the target SOC becomes a substitute for the permitted SOC. This eliminates the need to store and retain the permitted SOC, so that the calculation load can be reduced.

-The circuit configuration in the above embodiment may be arbitrarily changed. For example, as shown in FIG. 6, a two-switch circuit configuration may be adopted. The engine starter 10a, the generator 16 (alternator), the lead storage battery 11 and the electric load 13 are connected in parallel to the external terminal P0 of the battery unit U. The engine starter 10a has a function of starting the engine 10. Further, the generator 16 is drive-connected to the engine 10 and is configured to be capable of performing regenerative power generation and fuel power generation. An electric load 15 is connected to the external terminal P0 of the battery unit U. Further, when this circuit configuration is adopted, the engine starter 10a may be supplied with the electric power required for restarting the engine from the lead storage battery 11. In this case, the lower limit SOC is determined based on the minimum SOC required to supply the electric power required for stable operation of the electric load 15 connected to the lithium ion storage battery 12.

-In the above embodiment, as shown in FIG. 7, the first rotary electric machine 14a that executes power generation and the start of the engine 10 is driven and connected to the axle 10b, and the second rotary electric machine that can drive the vehicle can run. 14b and 14b may be provided separately. In FIG. 7, the lithium ion storage battery 12 is connected to the first rotary electric machine 14a and the second rotary electric machine 14b via the inverter 100. Further, the lithium ion storage battery 12 is connected to the lead storage battery 11 via the DC / DC converter 101. The lithium ion storage battery 12 is a high voltage battery (for example, a 300V battery) with respect to the lead storage battery 11. In this alternative example, the lithium ion storage battery 12 does not need to be limited to the lithium ion storage battery if it is a high voltage battery. Similarly, the lead-acid battery 11 does not have to be limited to the lead-acid battery as long as it is a low-voltage battery.

In this case, the lower limit SOC is the higher of the minimum SOC required for the second rotary electric machine 14b to restart the engine 10 and the minimum SOC required for the first rotary electric machine 14a to drive the vehicle. SOC is set.

-In the above embodiment, the deteriorated state and the temperature are adopted as the state of the lithium ion storage battery 12, but the information combining the output voltage (or output current) and the SOC is the state of the lithium ion storage battery 12 (related to the output performance). It may be adopted as a state). For example, when the output voltage is lower than the SOC, the lower limit SOC may be increased because it is considered to be deteriorated.

-In the above embodiment, when the SOC is less than the lower limit SOC, power may be supplied from the lead storage battery 11 to the rotary electric machine 14 to restart the rotary electric machine 14.

-In the above embodiment, the rotary electric machine 14 has a function of assisting the running of the vehicle (torque assist function), but if it has a function of starting the engine 10, it has a torque assist function. It does not have to be.

10 ... engine, 14 ... rotary electric machine, 15 ... electric load, 50 ... ECU, 51 ... lower limit value estimation unit, 52 ... power consumption estimation unit, 53 ... setting unit, 54 ... stop control unit, 55 ... start control unit.

Claims (11)

Applicable to a vehicle having an internal combustion engine (10), a starter (14) for starting the internal combustion engine, a storage battery (12) capable of charging and discharging, and an electric load (15) to which electric power is supplied from the storage battery. In the control device (50)
A stop control unit (54) that stops the internal combustion engine and shifts to the idling stop state when the automatic stop condition is satisfied, and
In the idling stop state, a start control unit (55) that controls the starter so as to restart the internal combustion engine when the restart condition is satisfied, and
A lower limit value estimation unit (51) that estimates a lower limit value, which is the remaining capacity of the storage battery, which is determined to be able to continue the idling stop state based on the state of the storage battery.
The power consumption estimation unit (52) that estimates the power consumption consumed by the electric load during the idling stop state, and the power consumption estimation unit (52).
It is the remaining capacity of the storage battery that permits the transition to the idling stop state in consideration of the power consumption estimated by the power consumption estimation unit based on the lower limit value estimated by the lower limit value estimation unit. It is equipped with a setting unit (53) for setting the permission value .
The electric load includes a constant voltage load in which the voltage of the supplied power is required to be constant or fluctuate within a predetermined range.
The lower limit value is a control device estimated based on the remaining capacity of the storage battery capable of outputting the minimum power required for stable operation of the constant voltage load in the idling stop state . The lower limit is the minimum required for the remaining capacity of the storage battery capable of outputting the minimum power required for restarting the internal combustion engine, or for stable operation of the constant voltage load in the idling stop state. The control device according to claim 1, wherein the remaining capacity of the storage battery capable of outputting the generated power is estimated based on the higher remaining capacity . The vehicle is provided with a generator capable of generating electricity from the driving energy of the internal combustion engine or the kinetic energy of the vehicle.
The storage battery is configured to be rechargeable by the electric power supplied from the generator.
A power generation control unit (56) for controlling the power generation of the generator is provided so that the remaining capacity of the storage battery becomes equal to or higher than the target value.
The control device according to claim 1 or 2, wherein the target value is set higher than the permitted value. When the remaining capacity of the storage battery is less than the target value after the end of the idling stop state, the power generation control unit utilizes the drive energy of the internal combustion engine or the kinetic energy of the vehicle until the target value is reached. The control device according to claim 3, wherein the power is continuously generated. The control device according to claim 3 or 4, wherein the permitted value is set only after the end of the idling stop state and until the remaining capacity of the storage battery reaches the target value. 3. The permission value is set when it is determined that the time from the end of the idling stop state to the re-establishment of the automatic stop condition is short based on the travel history of the vehicle or the peripheral information. The control device according to any one of 5 to 5 . The control device according to any one of claims 1 to 6 , wherein the power consumption estimation unit estimates the power consumption based on the travel history of the vehicle. The power consumption estimation unit does not make such a determination when it is determined that the frequency of transition to the idling stop state is high or when it is determined that the idling stop period is long based on the travel history of the vehicle. The control device according to claim 7 , wherein the power consumption is estimated to be larger than that in the case of the above. The control device according to any one of claims 1 to 8 , wherein the power consumption estimation unit estimates the power consumption based on the peripheral information of the vehicle. The power consumption estimation unit determines that the vehicle is congested, the road width is wide, or the frequency of appearance of traffic lights is high, based on the peripheral information of the vehicle. The control device according to claim 9 , wherein the power consumption amount is estimated to be larger than that in the case where such determination is not made. The start control unit according to any one of claims 1 to 10 , wherein the start control unit restarts the internal combustion engine based on a comparison between the remaining capacity of the storage battery and the lower limit value before the restart condition is satisfied. Control device.

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